1. Technical Field
The present invention relates generally to automotive vehicles, and more particularly to automotive frame assemblies and a method for manufacturing the same that employs fasteners requiring two-sided access for installation.
2. Background of the Invention
Structures of existing automotive frame assemblies (xe2x80x9cframe assembliesxe2x80x9d) and existing methods for manufacturing the same require substantial fusion welding of individual rail components and cross members to effectuate their assembly. The extensive use of fusion welding results in lengthy manufacturing cycle time.
A typical frame assembly includes at least one metal inner rail with at least one metal outer rail fixedly coupled thereto. Each rail is usually in the form of a stamped C-section. The inner rail and the outer rail are typically mated together in order to create a single rail in the form of a closed box beam.
In this typical construction, the inner rail and the outer rail are first stitched together by adjoining surfaces therebetween and then subsequently MIG welding at fixed distances. As is known in the art, MIG welding along entire lengths of adjoining surfaces assists in stabilizing dimensional requirements of the frame assembly. Thereafter, the remaining gaps along adjoining edges are typically MIG welded together. In comparison to resistance spot welding and self-piercing rivets, MIG welding may take about 30%-40% longer to fasten mating components together. Thus, the fusion welding process results in a lengthy manufacturing cycle time of these frame assemblies.
After the inner and outer rails have been joined, they are typically positioned in a fixture in a parallel configuration. The rails have a plurality of metal cross members positioned therebetween and perpendicular thereto. Each end of the cross members may have an L-bracket fusion welded thereto. Each L-bracket is then typically fusion welded to its respective rail thus creating the frame assembly.
The fusion welding typically transfers a substantial amount of heat to the metal components of the frame assembly. It is known in the art that certain metals are more susceptible to thermal expansion than others depending upon their respective coefficients of thermal expansion. Consequently, sufficient heat may be transferred to the metal components thereby increasing the size of the metal components. The increase in size during manufacture of the frame assembly may result in a construction that is beyond the design tolerances.
For example, aluminum metal may not be used in existing frame assemblies using current methods of frame assembly construction because its coefficient of thermal expansion is sufficiently high so as to cause the frame assembly upon completion of its manufacture to be outside the design tolerances. The inability to incorporate aluminum in frame assemblies is clearly unfortunate in view of several advantages offered by aluminum vehicular components. It is widely known that the use of aluminum components in automotive vehicles decreases the weight of the vehicle thereby improving fuel economy, emissions, and vehicle performance.
Further, the typical sequence in manufacturing a frame assembly impedes access to portions of the frame during manufacture thereof. For example, forming the rail in the shape of a closed box beam before the attachment of the cross members thereto prevents the use of two-sided fastening methods. The construction of the closed box beam obstructs access to the inner sides of the rail. Consequently, self-piercing rivets, resistance spot welding, and various other two-sided fastening methods typically may not be used to attach the cross members to the rails.
Moreover, the construction of the rail in the form of a closed box beam (opposing C-sections) prevents the subsequent reinforcement of the inner sides thereof.
Therefore, a need exists to provide a frame assembly and a method of manufacture thereof that reduces cycle time of manufacture, improves access to components during manufacture, and allows for dimensional stability.
The present invention provides an automotive frame assembly (xe2x80x9cframe assemblyxe2x80x9d) and a method for manufacturing the same that employs fasteners requiring two-sided access for installation therein so as to reduce the manufacturing cycle time without hindering compliance within the dimensional requirements.
There is disclosed herein a method for manufacturing an automotive frame assembly. The method includes providing an inner rail having an exterior side and an interior side. The inner rail has at least one flange fixedly attached thereto such that it extends from an end of a cross member. At least one two-sided fastener is operatively applied to the exterior side and the interior side of the inner rail so as to fixedly attach the flange to the inner rail. Thereafter, the inner rail has fixedly attached thereto at least one lip extending from an outer rail. Likewise, at least one two-sided fastener is operatively applied to the exterior side and the interior side of the inner rail so as to fixedly attach the lip to the inner rail.
One advantage of the present invention is that two-sided fasteners may be used to attach components of the frame assembly together. Another advantage of the present invention is that manufacturing cycle time is reduced. Still another advantage of the present invention is that dimensional control is provided despite the reduction in manufacturing cycle time.
Other advantages of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.